The invention relates to a method for imprinting optoelectronic components with at least one busbar, wherein the busbar follows the shaping of the optoelectronic component and enables a homogeneous color impression on the rear side of the component.
Optoelectronics is composed of the fields of optics and semiconductor electronics. It encompasses systems and methods which enable the conversion of electronically generated data and energies into light emission or convert light emissions into energy. Optoelectronic elements, in particular organic photovoltaic modules (PV module) and organic light emitting diodes (OLED), referred to hereinafter as OPV modules, generate electrical energy or convert electrical energy into light emissions, which has to be routed out of the module or routed in for application in the further course of the procedure. This necessitates so-called busbars, which have to meet the requirements of a flexible OPV module. Busbars constitute the point in an optoelectronic component at which the converted energy is concentrated and forwarded in the form of electric currents. Busbars are widely used in the semiconductor industry. As prior art, in the field of photovoltaics, busbars are known which are applied on the front side or on the rear side of the photovoltaic module in a rectangular or square shape. The dimensions of the cross section of a busbar depend on the current intensity to be transmitted. Busbars are applied by means of screen printing methods, inter alia. In this regard, DE102010054327A1 describes a method for producing a paste-application-selective screen printing solar cell metallization in which the layer thickness of the busbar is variable and the application volume of the silver paste is minimized, as a result of which production costs are lowered.
The shadow casting of busbars proves to be disadvantageous, this arising during paste printing on the front side of a photovoltaic module. Busbars printed from pastes had a defined height and width which cast a shadow on the photovoltaic module upon insolation and thus disadvantageously reduced the efficiency of the module.
A different procedure is evident from EP12497A1. Here the busbars are applied to the photovoltaic module in the form of metal strips. The shadow casting is thus minimized, but the solution proves to be unsatisfactory for transparent PV modules. The lower region of the busbar is not coated with absorber material, as a result of which a homogeneous color impression does not arise since the busbar remains visible from the rear side of the PV module. Furthermore, said metal strips can be applied in non-rectilinear geometries only with a disproportionate outlay.
Other solution approaches pursue the application of a busbar on the rear side of a PV module. CN000101707227B describes this process for a solar film, thereby counteracting the arising of air bubbles. The application of busbars on the rear side of a PV module additionally increases the efficiency since the entire front side of the PV module is available for energy production. This method also proves to be unsatisfactory for producing flexible transparent PV modules. As in the previously demonstrated solutions, the problem of the homogeneous color impression and the freedom of shape of the busbar routing remains.
Moreover, flexible PV modules have to meet stringent requirements. In this case, the cross connections of the busbars should be producible over the module width in order to route the negative and positive pole to a connection point. Moreover, the busbars must have the flexibility of the PV module. U.S. Pat. No. 7,795,067 B1 describes a flexible PV module having a flexible busbar, wherein a semitransparent solar cell is involved in that case and the busbar is visible.